US2907847A

US2907847A - Electrical switch structure

Info

Publication number: US2907847A
Application number: US665433A
Authority: US
Inventors: Aime J Grenier; Louis C Beggs; Robert G Mawney
Original assignee: Texas Instruments Inc
Current assignee: Texas Instruments Inc
Priority date: 1957-06-13
Filing date: 1957-06-13
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06
Also published as: DE1290227B; FR1188567A; GB876479A

Description

v m-um I! A. J. GRENIER ETAL 2,907,847

ELECTRICAL swncu STRUCTURE Oct. 6, 1959 3 Sheets-Sheet 1 Filed June 13, 1957 INVENTORS Am: J. enema-a, LOUIS c. azess noun 6. muimsv by mam, v9. Aggy.

Oct. 6, 1959 A. J. GRENIER ETAL 2,907,847

ELECTRICAL SWITCH STRUCTURE Filed June 13, 1957 s Sheets-Sheet 2 'y wmzw m. M

Oct. 6, 1959 Filed June 13, 1957 A. J. GRENIER ETAL 2,907,847

ELECTRICAL SWITCH STRUCTURE 3 Sheets-Sheet 3 28 INVENTORS AIME J. GRENIER, LOUIS G. BEGGS ROBERT e. MAWNEY y mam v0. Wm

United States Patent 2,907 ,847 ELECTRICAL SWITCH STRUCTURE Aini J. Grenier, Louis C. Beggs, and Robert G. Mawney, Attleboro, Mass., assignors to Texas Instruments, Incorporated, Dallas, Tex., a corporation of Delaware Application June 13, 1957, Serial No. 665,433 17 Claims. (Cl. 200-104) This invention relates to an electrical switch structure, and more particularly, to such a structure which includes a base or casing carrying one or more electrical terminals.

An object of this invention is the provision of such a switch structure, the component parts of which can be rapidly and easily assembled into and retained in operative condition.

A further object of this invention is the provision of such a switch structure which is compact, dependable in use, and economical to manufacture.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of the various possible embodiments of the invention is illustrated:

Fig. 1 is a perspective view of an electrical switch embodying the present invention;

Fig. 2 is a plan view thereof;

Fig. 3 is a plan view similar to Fig. 2, but with one of the casing members removed;

' Fig. 4 is a sectional view on a slightly enlarged scale and taken along line 4, 4 in Fig. 2;

Fig. 5 is a sectional view taken along line 5, 5 in Fig. 4; Fig. 6 is a sectional view taken along line 6, 6 in Fig. 2; Fig. 7 is a fragmentary sectional view taken along

line

7, 7 in Fig. 6;

Fig. 8 is a sectional view on a slightly reduced scale and taken along line 8, 8 in Fig. 4; Fig. 9 is a fragmentary sectional view taken along line 9, 9 in Fig. 8; and

Fig. 10 is an exploded perspective view of the electrical switch shown in Fig. 1.

Referring to Fig. 1, an electrical switch embodying the present invention is shown as being generally indicated by the reference numeral 20. Switch 20 takes the form of an electromagnetic relay and includes a pair of.

base or

casing members

22 and 24, respectively.

Casing members

22 and 24 are secured in interfitting engagement with each other by means of a stem 26 having a head 28,

the headed stem interfitting with apertures 27 and 29.

provided by

casing members

22 and 124, respectively, and being retained by a quick-attachable, push-on fastener 30. Fastener 30 may be of the well known type manufactured by Tinnerman Products, Inc., Cleveland, Ohio, and includes a pair of

jaws

32, 32 which bite into and prevent unintended retraction of the fastener from post 26 when the fastener is pressed thereover to the position shown in Fig 1.-

Mounted for slidable movement along stem 26 as best shown in Figs. 4 and 5 is a sleeve 34 formed of a suitable electrically insulating material such as nylon. Sleeve 34 provides

flanges

36 and 38, respectively, at its opposite ends for a purpose later to become apparent. Mounted for slidable movement on sleeve 34 is a hollow, cylindrical plunger weight 40 formed of a suitable magnetic material such as SAE 1113 steel. A movable, bridging contact member 42 provides an aperture 44 within which sleeve 34 is loosely disposed. Bridging contact member 42 is formed of a suitable, electrically conductive material such as phosphor bronze. A compression spring 46 resiliently biases plunger weight 40 away from the bridg ing contact member 42 and against flange 38 carried by sleeve 34. Spring 46 also resiliently biases bridging contact member '42 against washer 48 which, in turn, is biased against flange 36 provided by sleeve 34 as best shown in Figs. 4, 5 and 10. Sleeve 34, plunger weight 40, bridging contact member 42, spring 46 and washer 48 together form a plunger subassembly 49 which can be pre-assembled before assembling of the remaining parts of switch 20.

. Plunger subassembly 49 is actuated by means of a coil 50 formed by a plurality of mutually insulated turns of electrically conductive wire. When coil 50 is electrically energized, weight 40 is moved upwardly as viewed in Figs. 4 and 5 thereby to compress spring 46 whereby bridging contact 42 is moved upwardly to bring 1

movable contacts

52 and 54 into engagement with

fixed contacts

56 and 58, respectively. It is noted that the contacting surfaces of movable contacts 52 and 5'4 are curved about an axis lying at 90 to the axis of the curve of the contacting surfaces of

fixed contacts

56 and 58 whereby single point engagement is made between the respective contacts.

Fixed

contacts

56 and 58 are carried by

terminals

60 and 62, respectively, each of the latter being formed of a suitably electrically conductive material. Terminal 60 is provided with an aperture 64 within which a projection 66 is disposed. Projection 66 is fixedly carried by casing member 24 and extends from the bottom of a guideway 68 (see Figs. 1 and 10) provided by the interfitting surfaces of

casing members

22 and 24, extends through aperture 64 in terminal member 60 and into interfitting engagement with a recess in the form of a socket 70 provided by casing member 22. It will be noted that projection 66 facilitates alignment of terminal 60 and casing member 22 with casing member 24 when these parts are assembled together. Also, projection 66 prevents longitudinal movement of terminal 60 within guide way 68.

Guideway 68 includes a pair of

upstanding side walls

72, 72 which interfit with the respectively adjacent side portions of terminal 60 thereby to prevent substantial rotation of terminal 60 about the axis of projection 66. The bottom of guideway 68 is formed by a surface 74 provided by casing member 24 and the top of guideway 68 is formed by a surface 76 provided by casing member 22, all as viewed in Figs. 6 and 10.

Surfaces

74 and 76 interfit with the respectively adjacent portions of terminal 60 and thereby prevent vertical deflection of this terminal as viewed in Fig. 6. Accordingly, it will be apparent that merely by securing together casing member 22 and casing member 24, with terminal 60 therebetween, terminal 60 is securely retained in aligned tends through an aperture ,82 in terminal 62 into interfitting relation with arecess in the form of a socket 84 provided by easing member 22. .Guideway 78, projection 80, aperture 82 and socket-84am identical-in 7 Patented Oct. 6, 1959 carries a return-bent portion 90. Return-bent portion 90 may be secured to terminal 62 by welding the latter to leg 92' of the former. Preferably, return-bent portion 90 is secured to terminal 62 before assembly with the remaining parts of switch 20. The distal end of return bent portion 90' is formed by a leg 94 which, as shown in Figs. 1, 2, 3' and 8, is disposed in interfitting engagement with the bottom of slot 88. Return-bent portion 90' is, provided with a threaded aperture 96 for the reception of a lead-securing screw (not shown). It will be clear that, with leg 94 disposed in the bottom of recess 88', member 90 and terminal 62 are reinforced against deflection due to the torque thereon developed by tightening of a screw in threaded aperture 96.

By way of example, terminal 60 is illustrated in the drawing as being connected to a lead in a manner different from that of terminal 62. In this regard, a ferrule 98 which has been secured about the bared end of a lead 100 is welded to the protruding end of terminal 60. It will be realized, of course, that terminal 60 could be provided with a return-bent portion in the same manner and for the same purposes asv that described above with respect to terminal 62.

Referring particularly to Figs. 1, 4, 9 and 10, an additional terminal 102' is'shown as being incorporated by switch 20. As best shown in Fig. 9, terminal 102 is provided with a head 104, a portion of which lies in each of recesses 106 and 108, respectively. Recess 106 is provided by casing member 22 and communicates with a slot 110 which extends to the exterior of the casing. Recess 108 is provided by casing member 24 and communicates with a slot 112 which likewise extends to the exterior of the casing. As best shown in Fig. 10, slot 110 extends to the lowermost edge of easing member 22 to permit the assembly of easing member 22 with casing member 24 after positioning terminal 102 within recess 108 and slot 112 of casing member 24. It will be apparent that merely assembly and retaining

casing members

22 and 24 with terminal 102 therebetween results, as with

terminals

60 and 62, in terminal 102 being fixedly retained in operative relation with the remainder of the switch structure. Terminal 102 may be provided with a slot 114 for the reception of a lead 116 extending from one end of coil 50 as shown in Figs. 1, 2, 3, 4, 6, 8 and 10. Alternatively, the end of lead 116 may be welded to terminal 102', and a separate lead otherwise suitably connected to terminal 102.

Referring to Figs. 3 and 10, casing member 24 provides a plurality of projections 118 which are engageable with and guide bridging contact member 42, and prevent the latter from substantial rotation about the axis of stem 26.

Casing member 22 provides a pair of

projections

120 and 122. Projection 120 interfits within an aperture 124 provided by easing member 24. Projection 122 interfits with a slot 126 provided by easing member 24, which slot opens to one side of this casing memben. These projections and openings in the casing members aid in the alignment of the latter members during assembly thereof, and aid in preventing laterally relative movement between these casing members. A pair of shoulder-providing

members

128 and 130 aid in retaining coil 50 about cylindrical portion 132 of casing member v24. Shoulder-providing member 128 includes a relieved portion 134 as shown in Figs. and 10, for the reception of one of the end turns of coil 50. Reference numeral 136 refers to the opposite end of coil 50 from that to which lead'116 is connected.

Provision is made for the mounting of additional terminals on the casing-and for the mounting of the switch on its supporting structure, but since these features do not form a part of the present invention, no detailed description thereof is required.

Referring to Fig. 10, switch 20 may be assembled as follows. First, pin 26 is inserted into casing member 24 to bring the head 28 thereof against the lowermost edge of cylindrical portion 132. Plunger subassembly 49, having been pre-assembled, is then sleeved onto stem 26. The respective widths of aperture 124 and slot 126 in casing member 24 are less than the width of bridging contact member 42whereby unintentional disorientation of the bridging contact member with respect to the rest of the switch 20 is avoided.

Terminals

60, 62 and 102 are then assembled with casing member 24 in the positions described above, after which casing member 22 is disposed in interfitting engagement with the previously assembled structure. Fastener 3-0 is then pressed along stem 26 into engagement with the adjacent surface of casing member 22. Without more, casing

members

22 and 24,

terminals

60, 62 and 102, and the plunger assembly including plunger weight 40, sleeve 34, spring 46, and bridging contact member 42 are all securely and effectively retained in operative relationship as viewed in Fig. 1. It will be clear that connection of lead to terminal 60 may be effected either before or after assembly of terminal 60 with the remaining structure of switch 20. Likewise, coil 50 may be wound and connected as desired to terminal 102 before or after assembly of switch 20 is completed.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. Anelectrical switch structure comprising: a casing including a first casing member and a second casing member; means on the interior of each of said casing members providing complementary mutually interfitting interengaging surfaces which, when in interfitting interengagement, prevent relative movement between said members in at least one plane means retaining said casing members in interfitting engagement with each other; the interfitting surfaces of said casing members defining at least one guideway extending from the interior to the exterior of said casing; one of said casing members providing a recess opening to said guideway; an electrical terminal providing an aperture therethrough; said terminal being disposed in and confined against lateral movement by said guideway; and a projection carried by the other of said casing members; said projection extending through and interfitting with the aperture provided by said terminal and extending into interfitting engagement with said recess whereby the terminal is confined against movement with respect to said casing, and the terminal and said casing members are aligned with each other.

2. The electrical switch structure as set forth in claim 1 wherein one of said casing members provides a slot opening to said guideway and to the exterior of the ca"- ing; said terminal extending from the interior of the casing and including a return-bent portion; said return-bent portion of the terminal providing an internally threaded aperture for the reception of a lead-securing screw; and the distal end of said return-bent portion being disposed in said slot whereby the terminal is reinforced against substantial deflection perpendicular to the axis of said threaded aperture.

3. The electrical switch structure as set forth in claim 1 wherein each of said casing members provides a recess.

opening to said interfitting surfaces and provides a slot; each of said slots communicating with one of said lastmentioned recesses and with the exterior of the casing; said switch structure further including a headed terminal having a shank; a portion of the head of said last-mentioned terminal lying in each of said last-mentioned recesses; a portion of the shank of said headed terminal lying in each of said slots; and said shank extending from said head to the exterior of'the casing.

4. The electrical switch structure as set forth in claim 1 .Wherein said means comprises headed stem means extending through both of said casing members and secured at its distal end with a fastening means; said switch structure further including a fixed contact and a movable contact disposed within said casing; said fixed contact being carried by said terminal and means on one of said casing members carrying said movable contact for movement along said stem means into and out of engagement with said fixed contact.

5. An electrical switch structure comprising: a first casing member and a second casing member; each of said casing members providing an aperture in alignment with the aperture provided by the other; a stem interfitting with said apertures and having a head at one end; the head of said stem abutting an outer surface of one of said casing members; fastening means disposed about the stem adjacent the other end thereof and abutting an outer surface of the other of said casing members whereby the latter are retained in interfitting engagement with each other; means on the interior of each of said casing members providing complementary mutually interfitting interengaging surfaces which, when in interfitting interengagement, prevent relative movement between said members in at least one plane said means including a guideway defined by portions of the interfitting surfaces of said casing members with said guideway extending from the interior to the exterior of the casing; said first casing member providing a recess opening to said guideway; an electrical terminal disposed in said guideway and providing an aperture in alignment with said recess; a projection integral with and extending from said second casing member across said guideway and into interfitting engagement with the aperture provided by said terminal and with said recess provided by said first casing member, thereby aligning said terminal and the said casing members with each other and cooperating with said guideway to confine said terminal against movement relative to said casing members; an electrical contact carried by said terminal within said casing; a movable electrical contact, means on one of said casing members carrying said movable electrical contact for movement along said stem into and out of engagement with said first-named contact.

, 6. .The electrical switch structure as set forth in claim 3 wherein said shank, extending from said head to the exterior of the casing, includes electrical conductor fas tening means thereon in the form of an open-ended slot.

7. The electrical switch structure as set forth in claim 5 wherein said movable electrical contact is a bridging contact plunger subassembly comprising a sleeve, a conductive bridging contact member slidably supported thereon, magnetic armature means slidably supported on said sleeve and adapted upon energization by a surrounding coil to cause said contact member to move into contact with said first-named electrical contact and resilient means on said sleeve for transmitting motion from said armature to said bridging contact member; said means on one of said casing members carrying said movable electrical contact comprising a hollow housing in which said bridging contact plunger subassembly is guided and confined to reciprocating sliding movement axially of said sleeve, the exterior of said hollow housing providing a spool means for retaining an armature energizing coil thereon.

8. The electrical switch structure as set forth in claim 7 wherein said hollow housing is relatively thin-walled and cylindrical and includes shoulder means on the exterior of said housing at one end thereof for retaining a coil about the exterior of the cylindrical housing, said shoulder means including a relieved portion adapted to receive a portion of an armature energizing coil.

9. An electrical switch structure comprising: a casing including first and second casing members, each having means thereon providing complementary mutually interfitting, interengaging surfaces preventing relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement, said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact portion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said first-named means including a guideway defined by portions of the interfitting surfaces of said casing members and extending from the interior to the exterior of the casing, one of said members having a recess opening into said guideway, said terminal being disposed in and complementary in cross-sectional shape to that of said guideway and having an aperture formed therein in alignment with said recess, a projection extending from the other of said members through said guideway and into interfitting engagement with said aperture and recess in said terminal and said one member respectively, said projection, aperture, and recess aligning said terminal and casing members and cooperating with said guideway to confine said terminal against movement relative to said casing members, said first-named means further including at least one additional projection extending from one of said casing members toward the other of said casing members, adapted to be received in and interfit with a slot provided by the other of said casing members, thereby facilitating orientation and alignment of the casing mem bers and obviating relative movement therebetween in at least one plane.

10. The electrical switch structure as set forth in claim 9 further characterized by one of said casing members being provided with a slot spaced from and at an angle to said guideway, said terminal extending from the interior of the casing and including a return-bent portion having a lead-securing screw receiving means formed therein, and a portion disposed in said slot for reinforcing said terminal against substantial deflection and deformation.

11. An electrical switch structure comprising: a casing including first and second casing members, each having means on the interior thereof providing complementary mutually interfitting, interengaging surfaces preventing relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement; said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact portion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said first-named means including a guideway defined by portions of the interfitting surfaces of said casing members and extending from the interior to the exterior of the casing, one of said members having a recess opening into said guideway, said terminal being disposed in and complementary in cross-sectional shape to that of said guideway and having an aperture formed therein in alignment with said recess, a projection extending from the other of said members through said guideway and into interfitting engagement with said aperture and recess in said terminal and said one member respectively, said projection, aperture and recess aligning said terminal and casing members and cooperating with said guideway to confine said terminal against movement relative to said casing members, one of said casing members being provided with a slot spaced from and at an angle to said guideway, said terminal extending from the interior of the casing and including a return-bent portion having a lead-securing screw receiving means formed therein, and a portion disposed in said slot for reinforcing said terminal against substantial deflection and deformation.

12. An electrical switch structure comprising: a casing including first and second casing members, each having means on the interior thereof providing complementary mutually interfitting, interengaging surfaces preventing relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement with each other; said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact portion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact; said movable electrical contact further comprising a bridging contact plunger-type subassembly comprising a sleeve, said bridging contact portion slidably supported thereon for movement therealong into and out of engagement with said stationary contact, magnetic armature means slidably supported on said sleeve and adapted upon energization by a surrounding coil to move said bridging contact portion into contact with said stationary contact and resilient means on said sleeve for transmitting motion from said armature to said bridging contact portion, said means mounting said movable contact comprising a hollow housing on one of said casing members in which said bridging contact plunger subassembly is disposed and guided for reciprocating sliding movement axially of said sleeve, the exterior of said hollow housing providing a spool means for retaining an armature energizing coil, one of said casing members further including a bridging contact guideway in which said bridging contact portion is disposed and spaced projection means extending into said bridging contact guideway from one wall thereof, and engageable with said bridging contact portion to guide it and limit the direction of movement thereof only to movement into and out of engagement with said stationary contact.

13. The electrical switch structure as defined in claim 12 wherein said hollow housing is relatively thin-walled and cylindrical and includes shoulder means on the exterior thereof for retaining an armature energizing coil on said housing, said shoulder means including a relieved portion adapted to receive a portion of an armature energizing coil, said means retaining said casing members in interfitting engagement comprising a stem headed at one end, inserted respectively through aligned apertures provided by said cylindrical hollow housing, said sleeve of said plunger subassembly and each of said casing mem bers and fastening means disposed about the other end of said stem and abutting an outer surface of one of said casing members.

14. An electrical switch structure comprising: a casing including first and second casing members, each having means on the interior thereof providing complementary mutually interfitting, interengaging surfaces preventing relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement, said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact por tion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said first-named means including a guideway defined by portions of the interfitting surfaces of said casing members and extending from the interior to the exterior of the casing, one of said members having a recess opening into said guideway, said terminal being disposed in and complementary in cross-sectional shape to that of said guideway and hav ing an aperture formed therein in alignment with said recess, a projection extending from the other of said members through said guideway and into interfitting engagement with said aperture and recess in said terminal and said one member respectively, said projection, aperture and recess aligning said terminal and casing members and cooperating with said guideway to confine said terminal against movement relative to said casing members, one of said casing members being provided with a slot spaced from and at an angle to said guideway, said terminal extending from the interior of the casing and including a return-bent portion having a lead-securing screw receiving means formed therein, and a portion disposed in said slot for reinforcing said terminal against substantial deflection and deformation, said first-named means further including at least one additional projection extending from the interior of one of said casing members towardthe other of said casing members, adapted to be received in and interfit with an interiorly opening slot provided by the other of said casing members, thereby facilitating orientation and alignment of the casing members and obviating relative movement therebetween in at least one plane, one of said casing members further including a bridging contact guideway in which said bridging contact portion is disposed, spaced projection means extending into said bridging contact guideway from one wall thereof and engageable with said bridging contact portion to guide it and limit the direction of movement thereof only to movement into and out of engagement with said stationary contact.

15. An electrical switch structure comprising: a'casing including first and second casing members, each having means on the interior thereof providing complementary mutually interfitting, interengaging surfaces preventing tion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said first-named means including a guideway defined by portions of the interfitting surfaces of said casing members and extending from the interior to the exterior of the casing, one of said members having a recess opening into said guideway, said terminal being disposed in andcomplementary in cross-sectional shape to that of said guideway and having an aperture formed therein in alignment with said recess, a projection extending from the other of said members through said guideway and into interfitting engagement with said aperture and recess in said terminal and said one member respectively, said projection, aperture, and recess aligning said terminal and easing members and cooperating with said guideway to confine said terminal against movement relative to said casing members, one of said casing members further including a bridging contact guideway in which said bridging contact portion is disposed and spaced projection means extending into said bridging contact guideway from one wall thereof and engageable with said bridging contact portion to guide it and limit the direction of movement thereof only to movement into and out of engagement with said stationary conta'ct;'the transversedimension of said bridging contact portion being greater than that of said first-named guideway and said interiorly opening slot so as to avoid disorientation thereof, said first-named means further including at least one additional projection extending from the interior of one of said casing members toward the other of said casing members adapted to be received in and interfit with an interiorly opening slot provided by the other of said casing members, thereby facilitating orientation and alignment of the casing members and obviating relative movementtherebetween in at least one plane. i

16. An electrical switch structure comprising; a casing including first and second casing members, each having means on the interior thereof providing complementary mutually interfitting, interengaging surfaces pre venting relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement, said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact portion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said movable electrical contact further comprising a bridging contact plunger-type subassembly comprising a sleeve, said bridging contact portion slidably supported thereon for movement therealong into and out of engagement with said stationary contact, magnetic armature means slidably supported on said sleeve and adapted upon energization by a surrounding coil to move said bridging contact portion into contact with said stationary contact and resilient means on said sleeve for transmitting motion from said armature to said bridging contact portion, said means mounting said movable contact comprising a hollow housing on one of said casing members in which said bridging contact plunger subassembly is disposed and guided for reciprocating sliding movement axially to said sleeve, the exterior of said hollow housing providing a spool means for retaining an armature energizing coil, one of said casing members further including a bridging contact guideway in which said bridging contact portion is disposed, and spaced projection means extending into said bridging contact guideway from one wall thereof, and engageable with said bridging contact portion to guide it and limit the direction of movement thereof only to movement into and out of engagement with said stationary contact; said first-named means further including at least one additional projection extending from the interior of one of said casing members toward the other of said casing members adapted to be received in and interfit with an interiorly opening slot provided by the other of said casing members, thereby facilitating orientation and alignment of the casing members and obviating relative movement therebetween in at least one plane.

17. An electrical switch structure comprising: a casing including first and second'casing members, each having means on the interior thereof providing complementary mutually inter-fitting, interengaging surfaces preventing relative movement therebetween in at least one plane, means retaining said casing members in interfitting engagement, said switch including a stationary terminal having at least one electrical contact thereon and a movable electrical contact having a bridging contact portion, means mounting said movable contact on said switch for reciprocal movement into and out of engagement with said stationary contact, said first-named means including a guideway defined by portions of the interfitting surfaces of said casing members and extending from the interior to the exterior of the casing, one of said members having a recess opening into said guideway, said terminal being disposed in and complementary in cross-sectional shape to that of said guideway and having an aperture formed therein in alignment with said recess, a projection extending from the'other of said members through said guideway and into interfitting engagement with said aperture and recess in said terminal and said one member respectively, said projection, aperture and recess aligning said terminal and casing members and cooperating with said guideway to confine said terminal against movement relative to said casing members, one of said casing members further including a bridging contact guideway in which said bridging contact portion is disposed and spaced projection means extending into said bridging contact guideway from one wall thereof and engageable with said bridging contact portion to guide it and limit the direction of movement thereof only to movement into and out of engagement with said stationary contact; the transverse dimension of said bridging contact portion being greater than that of said first-named guideway so as to avoid disorientation of the bridging contact.

References Cited in the file of this patent UNITED STATES PATENTS 2,562,420 Furnas July 31, 1951 2,640,970 Falge et a1. June 2, 1953 2,649,514 Ballou Aug. 18, 1953 2,653,198 Krenke Sept. 22, 1953 2,723,327 Gilbert Nov. 8, 1955 2,765,381 Smith Oct. 2, 1956 2,804,519 Slonneger Aug. 27, 1957 FOREIGN PATENTS 692,074 Germany June 12, 1940